This invention relates to apparatus for measuring thermal quantities and the like and more particularly to an instrument known as a "bomb calorimeter" adapted to measure thermal quantities in combustible substances.
Bomb calorimetry is a means of accurately determining how much heat is released when a given weight of a combustible substance is burned in oxygen.
Typically this is carried out in a pressure vessel (bomb) in which the fuel is electrically ignited in a high pressure oxygen environment, producing a temperature increase. This increase is measured and used to calcualate the "calorific value", and other quantities.
Various types of bomb calorimeters have been developed including the "adiabatic" calorimeter and the "isothermal" or "isoperibol" calorimeter both of which have been modified in various ways in order to maximise the accuracy, speed of operation, or efficiency of the instrument. Both types of calorimeters include removable bombs which are loaded with the combustible substance, the bomb thereafter being inserted into the instrument and connected to various measuring devices from which readings are taken. The readings which are taken during the test are used to determine the calorific value of the substance.
In isothermal calorimetery it is necessary to determine an initial temperature gradient before firing as well as usually a final temperature gradient after firing. Both these determinations are time consuming.
Calorimeters have invariably used multiple bombs in order to speed up the time taken to perform individual tests. This enables one bomb to be loaded while another is being analysed.
Bomb design and construction has largely adhered to a fairly standard format, with a removable lid, or base, secured to the main bomb body by a threaded cap, cumbersome to load and prone to wear, rendering the bomb itself a source of concern and even danger. Accidents have occured where threaded caps have blown off explosively.
A loaded bomb therefore constitutes a major handling hazard, and can fail even if knocked over or dropped.
Bomb calorimetry tends to be a labour intensive operation, due to the multiple manual steps in bomb loading, fusing and pressurising.
It is an object of this invention to provide apparatus of the aforementioned type which is accurate, and which in at least some applications is more efficient than prior art similar apparatus.